As described in, for instance, Non-patent Literature (Nanfang Yu, et al. “Light Propagation with Phase Discontinuities: Generalized Laws of Reflection and Refraction,” SCIENCE, VOL 334, pp. 333-337, 21 Oct. 2011), a metasurface for modulating and outputting input light is known. The metasurface described in this document includes a Si substrate including a light input surface into which input light is input and a light output surface facing the light input surface, and a plurality of V-shaped antenna elements disposed on the light output surface of the Si substrate, and modulates input light including a wavelength band of 8 μm.